SAN LUCAS THRASHER 381 



minally with the same ; markings on underparts much smaller, more 

 linear." 



The markings on the underparts are also more numerous on young 

 birds than on adults. I have no information on the molts, which are 

 probably similar to those of the other desert thrashers. Mr. Brewster 

 (1902) says: "Autumn birds are much more ashy above and buffy be- 

 neath than spring specimens. In some of the former, the wing coverts 

 are tipped with rusty, and the flanks, abdomen, crissum, and under tail 

 coverts with light rusty ochraceous. As the season advances, these 

 colors gradually fade, until by April the upper parts become dull 

 ashy brown, while the abdomen and crissum are only faintly tinged 

 with rusty. In June the plumage is excessively worn and faded, and 

 the underparts are essentially uniform soiled white." 



Field marks. — Birds of this species are somewhat like sage thrashers 

 in general appearance and behavior, but the sage thrasher is not likely 

 to be seen in Baja California except in winter and is not very common 

 then. The San Lucas thrasher is a much larger bird than the sage 

 thrasher, has a much longer and more curved bill, and has somewhat 

 less white on the tips of the lateral tail feathers. 



Enemies. — ^Mr. Bancroft says in his notes: "The life problem of 

 cinereum consists far more in obtaining food than it does in escap- 

 ing enemies. There is little evidence that the depredations of the lat- 

 ter are a serious deterrent to an increase in the number of birds; 

 if the contrary were true, I am sure that we who are familiar with 

 Lower California would have sensed it. Sharp-shinned and pigeon 

 hawks definitely are not factors. Nor are nocturnal birds of prey, in 

 my studied opinion. I do not see how owls can catch thrashers in 

 appreciable numbers. Certainly not without leaving traces which 

 we could hardly have failed to detect. This same line of thought ap- 

 plies to predatory animals. Furthermore, though there are quite a 

 few varieties, individually their relative number is small and all are 

 utterly dependent on other than avian prey for maintenance. 



"The worst offender is the gopher snake, Pituophis vertebralis. 

 Occasionally I have found one that has climbed into a garambullo, or 

 even a cardon, in apparent search for eggs or nestlings. However, 

 if these reptiles often met with success, they would leave traces that 

 are noticeably absent, records plain enough for all to read. As a mat- 

 ter of fact, snakes are not at all abundant on the southern deserts; 

 three times only have I seen one engaged in one of these forays." 



DISTRIBUTION 



Range. — Baja California; nonmigratory. 



The species ranges north in Baja California to a little north of 

 latitude 31° (San Antonio del Mar and San Telmo) . East to central 



